A balance between supply and demand must be determined to meet the parking requirements of motorists. The ability to efficiently allocate and manage on-street parking remains elusive, even when parking requirements are significant, recurring, and known ahead of time. For instance, urban parking spaces characteristically undergo periods of widely skewed demand and utilization, with low demand and light use in some periods, often during the night, and heavy demand and use at other times. Real-time parking occupancy detection systems are an emerging technology in parking management.
Some prior art parking occupancy detection approaches utilize a puck-style sensor configuration that outputs a binary signal when detecting a vehicle in, for example, a parking stall or a particular parking spot. FIG. 1, for example, illustrates respective parking occupancy detection system 100 for parking occupancy detection in an on-street parking. In the example depicted in FIG. 1, system 100 includes one or more puck-style in-ground sensors 102, 104, 106. Also depicted in FIG. 1 are example parking spaces 110, 108, 112, 114. A vehicle 116 is shown parked in parking space 108 in FIG. 1. The vehicle 116 can be detected by a sensor similar to 102, 104, and 106 located in parking space 108 underneath the vehicle 116. In the example shown in FIG. 1, the sensors 102, 104, and 106 can provide real-time data in order to aid drivers searching for the parking spots and to reduce traffic congestion in cities due to drivers circling about parking lots in a wasteful and time consuming effort to find parking spots.
On-street/curbside parking space reservation systems have also been proposed based on inputs from in-ground sensors. Such prior art parking space management and reservation systems are based on the use of binary sensor input data for determining parking spot availability only. Hence, customers are unable to preview the parking space before making a reservation or arriving at the desired parking spot.
Video-based parking occupancy detection systems, an example of which is shown in FIG. 2, are a recently developed technology. The video-based parking occupancy detection system shown in FIG. 2, for example, generally includes an image-capturing unit 152 (e.g., a video camera) mounted on, for example, a pole 151. The image-capturing unit 152 monitors within its field of view one or more vehicles 154, 156, 158 respectively parked in parking spaces 160, 162, 164.
FIG. 3 illustrates an ultrasonic parking sensor system that includes one or more ultra sonic sensors 176, 178, 180 deployed, for example, in a ceiling of a parking garage with respect to parking spaces 171, 173, 175 in which respective vehicles 170, 172, and 174 are parked.
The ability to identify a vehicle in an on-street parking situation is technologically difficult. In-ground sensor technology is inheritably not capable of identifying vehicles with precision. It is difficult even for video-based parking occupancy detection technology because once a vehicle is parked there is not always a good angle for a camera to take an image of the vehicle's license plate. One previous suggestion involved using one camera to capture the license plate of a vehicle before (or after) parking while another to track the vehicle to (or from) its parking position. However, robust vehicle tracking at street traffic condition is still an open and difficult research topic.
Vehicle identification is important for on-street parking management applications such as an automatic parking payment system where a user is allowed to set up an account for parking. Correct association of a parking vehicle with its account is crucial for charging the correct amount of a parking fee to a user. Correct association between parking vehicles and parking accounts is also important for municipal authorities as on-street parking violation enforcement is an important problem and is also a great source of revenue for municipalities, cities, local governments, etc.
Another proposal involves identifying the parking vehicle and associate it with an pre-arranged payment method. An in-car device that incorporates GPS and additional sensors can be installed inside the vehicle. This in-car device can act as an identifier among other vehicles in the area. While this solution solves the problem of identifying each parking vehicle, it has several drawbacks. First, a user's privacy may be compromised as the vehicle is forced to include the device all the time, and someone else other than the user knows where the user is all the time. Obviously, many users may not like this method. Secondly, the solution requires participating garages or street blocks to give a GPS location boundary map to know when a participating vehicle enters the boundary.